Lithium ion conducting membranes

ABSTRACT

A lithium ion conducting membrane and methods of making the same. The membrane includes a polymeric matrix and a plurality of ion-conducting particles disposed within the polymeric matrix. An inorganic coating deposited in the polymeric matrix.

GOVERNMENT SUPPORT CLAUSE

This invention was made with government support under Contract No.DE-AC02-06CH11357 awarded by the United States Department of Energy toUChicago Argonne, LLC, operator of Argonne National Laboratory. Thegovernment has certain rights in the invention.

TECHNICAL FIELD

The present disclosure relates generally to methods for production oflithium. More specifically the present disclosure describes methods forand compositions of lithium produced by electrodeposition.

BACKGROUND

Lithium metal is an attractive material for use as an anode in batteriesdue to being the lightest and most electropositive metal with atheoretical specific coulometric capacity of 3860 mAh/g, density of 0.59g/cm³, and negative reduction potential of −3.040V vs. standard hydrogenelectrode (“SHE”). Lithium is expected to play an increasingly largerole in the energy needs as more consumer demand shifts from petroleumproducts to electricity. Common Li-ion batteries used for energy storagehave a graphite anode and a lithium containing cathode, typicallyLiCoO₂.

However, use of lithium metal as an anode in rechargeable batteries hasbeen plagued by several issues that cause its use to be extremelylimited. A limited life cycle is one of the most critical issues withthe technology both in terms of cost and feasibility. Most of the issuesrelate to the formation of dendrites during cycling. During the firstfew cycles of a cells life a solid-electrolyte interphase (“SEI”) isgenerated at the surface of the anode. The SEI consumes some of theavailable lithium in its makeup. When dendrites are formed duringcontinued cycling, more and more lithium is consumed in the generationof SEI on the surface of the dendrites, resulting in continued capacityfade. In addition, dendrites can grow long enough to penetrate theseparator and short the cell causing immediate failure.

In addition, current production methods for lithium metal involve hightemperature electrolysis of a mixture of molten lithium chloride andpotassium chloride that is relatively energy intensive. Typically,commercial production of lithium involves forming the metal usinglithium chloride as a feedstock in a high temperature reaction vessel.In one process, a ratio of 55% LiCl is mixed with 45% KCl to produce amolten eutectic electrolyte. That material is fused and electrolyzed atabout 450° C. This releases the chlorine as a gas, leaving moltenlithium, which slags out or rises to the surface of the electrolyte.This requires collecting the lithium in this environment, in particularin a manner to prevent oxidation of the lithium such as by wrapping inparaffin or the like. The resultant lithium material may be presented asbulk material, such as an ingot, or as a foil to be used with asubstrate material. However, for the foil usage, it is necessary tolaminate or adhere the lithium foil to the substrate as a separateprocess.

Some researchers have attempted to address the failings of thecommercial lithium production process. These process attempted toproduce nanostructured lithium (rod/columnar morphology) films on a Cufoil using a commercially available Li metal foil. In one attempt atTsinghua University (China), galvanostatic deposition was developed in atwo-electrode system (Cu, Li foil) using 1M LiTFSI in 1:1 DOL:DME atfixed capacities of 1 mAh/cm² (at various current densities 0.1, 0.5, 1and 2 mA/cm²) or at 0.25 and 0.5 mAh/cm² (at 0.5 mA/cm²); columnardiameter ca. 300 nm; and lengths 1−5 μm (Cheng, et al., Angew. Chem.Int. Ed. 10.1002/anie.201707093).

In another attempt, the Pacific Northwest National Laboratory used Limetal deposited onto Cu foil in 1M LiPF₆ in PC with up to 200 ppm H₂Oadditive at 0.1 mA/cm² for 15 h to give nanorod diameter 260 nm andlength 9 μm (Qian, et al., Nano Energy 2015, 135-144); or with 0.05MCsPF₆ additive to produce 30 nm diameter rods (Zhang, et al., Nano Lett.2014, 14, 6889-6896).

In yet another attempt, Xiamen University (China) focused ongalvanostatic or potentiostatic deposition on Cu working electrode froma Li foil using 1M LiPF₆ in organic solvent (PC, 2:1 EC:DMC) with 50 ppmH₂O additive at fixed current density of 0.1 mA/cm² for up to 400 min;nanorod diameters 200-300 nm (Tang et al. J. Raman Spectrosc. 2016, 47,1017-1023).

Thus, there remains a need for a lower cost, lower energy consumptionprocess for forming lithium, particularly lithium that is resistant tothe life cycle issues with current production results as well as beingamenable to direct foil formation on substrates.

SUMMARY

Certain embodiments described herein relate generally to a hybridinorganic/organic membrane. The membrane comprises a polymeric matrix; aplurality of ion-conducting particles disposed within the polymericmatrix, the plurality of ion-conducting particles forming ion conductingchannels in the polymer matrix; and an inorganic coating deposited inthe polymeric matrix, the inorganic coating being a uniform layer 1 to10,000 atoms thick.

Certain embodiments described herein relate generally to a method ofmaking a hybrid inorganic/organic membrane. The method comprises:forming a polymer framework having a plurality of pores; and integratinga plurality of ion conducting particles into the polymer framework.

It should be appreciated that all combinations of the foregoing conceptsand additional concepts discussed in greater detail below (provided suchconcepts are not mutually inconsistent) are contemplated as being partof the subject matter disclosed herein. In particular, all combinationsof claimed subject matter appearing at the end of this disclosure arecontemplated as being part of the subject matter disclosed herein.

BRIEF DESCRIPTION OF DRAWINGS

The foregoing and other features of the present disclosure will becomemore fully apparent from the following description and appended claims,taken in conjunction with the accompanying drawings. Understanding thatthese drawings depict only several implementations in accordance withthe disclosure and are therefore, not to be considered limiting of itsscope, the disclosure will be described with additional specificity anddetail through use of the accompanying drawings.

FIG. 1 illustrates a general electrodeposition apparatus in accordancewith one embodiment.

FIG. 2 illustrates one embodiment for a method for electrodeposition oflithium.

FIG. 3A is an SEM photomicrograph of lithium metal deposited on a copperfilm in accordance with one embodiment. FIG. 3B is an enlargement of theindicated portion of FIG. 3A showing a perspective view of the lithiumstructures, with the elongated lithium rods and hemispherical tipsvisible. FIG. 3C is an enlargement of the indicated portion of FIG. 3Ashowing the hemispherical tips.

FIG. 4A is a SEM photomicrograph of the deposited lithium, with theinset showing an enlarged view of the lithium columns/rods. FIG. 4Billustrates another view of the deposited lithium rods indicating thedimension corresponding to diameter. FIG. 4C is yet another view of thedeposited lithium rods indication the dimension corresponding to length.

FIG. 5A illustrates a side view of a cross-section of lithium metal on acopper foil with a thickness of 30 μm serving as an anode. FIG. 5Billustrates the same copper foil and lithium metal anode but after usagein a battery, with the thickness reduced to 20-25 μm; FIG. 5C shows thelithium metal layer on the initially bare copper foil cathode; FIG. 5Dshows the lithium metal with the plane of redeposition indicated wherelithium metal is deposited during current reversal (recharge). FIG. 5Eillustrates cycling tests (Arbin or LANHE LAND testers) for coin cellsmade with electrodeposited lithium metal. FIG. 5E shows cycling voltagein red and current in blue as a function of cycling or test time) forsymmetrical coin cell of electrodeposited Li vs. electrodeposited Li,and FIGS. 5F-G show cycling voltage and current, respectively, (testtime on x-axis) for asymmetrical coin cell of electrodeposited Li vs.NMC 532 at C/10 rate in Gen 2 electrolyte (1.2M LiPF₆ in 3:7 EC:EMC).The electrodeposited Li on Cu foil used as anodes consist ofdensely-packed dendrite-free arrays of nanorods typically ≥25 μm inlength.

FIG. 6 illustrates one embodiment of a system for electrodeposition oflithium comprising a two half-cell structure.

FIG. 7 illustrates the two half-cells of FIG. 6.

FIG. 8A is an image of a half-cell with the cathode (copper), thedeposited material visible on the cathode. FIGS. 8B-D are SEM images ofthe blue deposit on copper foil of FIG. 8A, showing uniform,densely-packed, dendrite-free lithium metal nanorods produced in a glassflow cell with a hybrid polymer-inorganic oxide membrane. FIG. 8B is at7.99 k (ca. ×8,000) magnification; FIG. 8C is at ×50,000 magnification;and FIG. 8D is at ×13,000 magnification.

FIG. 9 shows a schematic of one embodiment of a hybrid nanocompositemembrane featuring a polymer framework containing an array oflithium-ion conducting nanomaterials columns.

FIGS. 10A-10C illustrate an embodiment of a polymer framework that was3D printed.

FIGS. 11A-11C are photomicrographs demonstrating structure of oneembodiment of a lithium permeable membrane using a polymer support withLiFePO₄ encapsulated in the pores of the polymer support via interfacialpolymerization.

FIG. 12 is a graph of polymer thickness over time from exposure to threedifferent concentrations of Pronase E.

FIGS. 13A-C show photomicrograph images of one embodiment of an ALDcoated hybrid membrane; FIG. 13A shows the top view of the membrane withthe constitute nanoparticles visible, FIG. 13B shows a side view (240micron thickness), while FIG. 13C shows the aluminum oxide overcoat.

FIGS. 14A-C shows an elemental analysis via X-ray fluorescence (“XREF”)of one embodiment of a membrane (FIG. 14A) and of membranes fabricatedby ALD/SIS treatment (FIGS. 14B-C). The XREF signal (y-axis) is plottedas a function of photon energy (x-axis, units keV). FIG. 14A shows theuntreated membrane; FIG. 14B shows a TMA/H₂O treated membrane has beencoated with aluminum oxide; FIG. 14C shows a DEZ/H₂O treated membranehas been coated with zinc oxide.

FIGS. 15A-D are scanning TEM images (scale bar: 1 μm) (FIG. 15A) indark-field of a sample cross-section prepared via focused ion beam, withcorresponding EDS mapping (FIGS. 15B-D) of SEI composition consistingmostly of (FIG. 15B) carbon and fluorine (FIG. 15C) from decompositionand/or side-products of electrolyte (LiPF₆). FIG. 15D shows the resultsof a lithium sample that was exposed to a nitrogen gas flow toindirectly map lithium via Li₃N formation.

FIG. 16A illustrates a cathode with deposited lithium metal with an axisA-B; FIGS. 16B-C are micrographs of the cross section along A-B in FIG.16A for the side of the cathode facing the membrane and nearest theatmosphere (argon)/catholyte interface; FIGS. 16D-H are micrographs ofthe cross section along A-B in FIG. 16A for the side of the cathodefacing the membrane and furthest from the atmosphere (argon)/catholyteinterface. Nanorod structure is observed most at the locations on theside facing the membrane and away from the atmosphere/catholyteinterface.

FIG. 17 shows atomic concentration as etching of an electrodepositedfilm.

FIG. 18 shows a comparison of electron energy loss spectra (“EELS”) fora sample of electrodeposited lithium metal film and itsfluorine-containing SEI with reference materials shows that acomposition of this fluorine-containing SEI may in part be lithiumfluoride (LiF).

FIGS. 19A-B show SEM images of lithium metal electrodes in coin cellsthat were cycled and then opened show that a commercial lithium foilwithout this fluorine-containing SEI develops a significantly thickermossy and/or dendritic lithium growth as seen in the right panels ofFIG. 19A (electrodeposited by one embodiment) and in the left panels ofFIG. 19B (commercial lithium foil).

Reference is made to the accompanying drawings throughout the followingdetailed description. In the drawings, similar symbols typicallyidentify similar components, unless context dictates otherwise. Theillustrative implementations described in the detailed description,drawings, and claims are not meant to be limiting. Other implementationsmay be utilized, and other changes may be made, without departing fromthe spirit or scope of the subject matter presented here. It will bereadily understood that the aspects of the present disclosure, asgenerally described herein, and illustrated in the figures, can bearranged, substituted, combined, and designed in a wide variety ofdifferent configurations, all of which are explicitly contemplated andmade part of this disclosure.

DETAILED DESCRIPTION OF VARIOUS EMBODIMENTS

Embodiments described herein relate generally the use of a roomtemperature electrodeposition method and the optimization of processparameters and conditions to produce a film of nanostructured lithiummetal onto a conductive substrate from an aqueous source of lithium ionsthrough a lithium-ion conducting separator. As used herein “roomtemperature” shall mean temperatures within 15 to 40° C.

In one embodiment, an electrolytic cell is utilized for the productionof lithium. FIG. 1 illustrates one embodiment of a lithium productionsystem 100 having the electrolytic cell 110. The electrolytic cell 110includes a cathode 120 and an anode 130, preferably disposed in ahousing 111. The cathode 120 is positioned to be disposed in a catholytewhile the anode is positioned to be disposed in an anolyte. During theelectrolytic production process, the anode serves as the positiveterminal and the cathode as the negative terminal. Separating thecathode 120/catholyte 121 from the anode 130/anolyte 131 is a membrane140. The membrane 140 is a lithium permeable membrane, allowing lithiumfrom the anolyte to cross from the anode to the cathode, passing throughthe membrane 140.

The system 100 further includes the anolyte supply subsystem 134 incommunication with the electrolytic cell 110 to provide anolyte. Theanolyte supply system provides renewable source of lithium. In oneembodiment, the catholyte 121 is provided and replenished by a catholytesupply system 225. The catholyte supply system 225 and the anolytesupply system 272 are best shown in FIGS. 7 and 8A where a peristaltictube may be connected to the respective anode half-cell and cathodehalf-cell. In the embodiment of FIG. 1, the membrane 140 which isadhered to an assembly for the cathode to create a well into which alimited amount of catholyte can be poured into and the cathode substrateimmersed in. Thus, in the embodiment of FIG. 1, the catholyte is notreplenished.

A galvanostat 160 is provided in electrical with the cathode andelectrode. The galvanostat 160 is configured to supply and, in apreferred embodiment, measure both the current applied to theelectrolytic cell 110 and the resulting full cell voltage. The anode 130receives current from galvanostat 160. The galvanostat 160 may beprovided with a reference electrode 161 with a known electrode potentialand electrolyte to provide a point of reference, such as the use of acommercially available reference immersed in the anolyte. Furtherdetails on the individual components of a lithium production system aredescribed below.

Another embodiment of the invention relates to a method or producinglithium. For example, one method of production utilizes a system such asshown in FIG. 1. FIG. 2 illustrates the steps of an embodiment for theproduction of lithium. A current is applied to the electrolytic cell atthe anode. The anolyte is oxidized at the anode, releasing electronsthat flow through the galvanostat to the cathode. At the cathode, theLithium cations are reduced and deposited as lithium metal on thecathode. Lithium ions flow through the membrane 140 to maintain thecharge balance as lithium ions are reduced to neutral lithium metal. Acombination of advanced electron microscopy imaging techniques andspectroscopic elemental composition reveals that each lithium metalnanorod is coated by a thin, solid electrolyte interphase SEI whosecomposition depends on the catholyte used. The anodic half-reaction:H₂O_((liq))→½ O_(2(gas))+2 H⁺ _((aq))+2 e⁻. The cathodic half-reaction:Li⁺ _((aq))+1 e⁻→Li_((s)). In particular, embodiments of theroom-temperature electrolysis are different from the current commercialproduction of lithium metal via molten salt electrolysis. Commerciallithium is made by passing current through a molten salt mixture oflithium chloride and potassium chloride (the latter added to increasethe mixture's conductivity. This process requires energy-intensiveheating to an elevated temperature of 450° C., and producesnon-environmentally friendly chlorine (Cl₂) gas as a by-product.

A fluorine-containing SEI layer that is formed under the particular setof electrodeposition conditions detailed herein is advantageous for theperformance of lithium metal films (produced in this manner) as anodesin batteries. A combination of advanced electron microscopy imagingtechniques and spectroscopic elemental composition reveals that thislithium metal is covered by a thin, solid electrolyte interphase (SEI)whose composition may depend on the catholyte used. X-ray photoelectronspectra of a sample of electrodeposited lithium metal film confirms thepresence of this fluorine-containing SEI produced during theelectrodeposition process. The lithium and fluorine appear to havesteady-state concentrations throughout argon ion plasma etching of asample of electrodeposited lithium metal film, suggesting fluorine iscontained within the electrodeposited lithium anode as seen in FIG. 17.

FIG. 18 shows a comparison of (EELS for a sample of electrodepositedlithium metal film and its fluorine-containing SEI with referencematerials shows that a composition of this fluorine-containing SEI mayin part be lithium fluoride (LiF).

Surprisingly, this fluorine-containing SEI, which may exist residuallywithin the electrodeposited lithium anode, is beneficial to batteryperformance by minimizing the growth of mossy and dendritic lithium thatoccurs during battery cycling. SEM images of lithium metal electrodes(either commercial lithium foil or our electrodeposited lithium metal oncopper foil) in coin cells that were cycled and then opened show that acommercial lithium foil without this fluorine-containing SEI develops asignificantly thicker mossy and/or dendritic lithium growth as seen inFIG. 19A (electrodeposited by one embodiment) and FIG. 19B (commerciallithium foil).

In one embodiment, the method of production includes one or more processparameters. The process parameters may be controlled to provide adesired result. In one embodiment, the process parameters includecathode materials, anode materials, current density, duration ofelectrodeposition time, electrolyte composition, and substrateproperties (including material, surface texture, and pre-treatment). Thedescribed system operates in an atmosphere. In one embodiment, the cellcan be operated outside of a controlled a glovebox and in ambient, aslong as the electrodeposited lithium metal film is protected from air(particularly from oxygen, nitrogen, moisture and carbon dioxide) with athin coat of non-evaporating organic solvent (e.g., by immediatelydipping in propylene carbonate after electrodeposition). Lithium metalreacts with the components of air as follows:

2Li+½O₂→Li₂O;  (1a)

Li₂O+H₂O→2LiOH;  (1b)

2 LiOH+CO₂→Li₂CO₃+H₂O;  (1c)

3Li+½N₂→Li₃N.  (2)

One process parameter that can be varied is Lithium feedstock flow rate.There is expected to be an optimum lithium feedstock flow rate, as theconcentration of lithium ions in the catholyte needs to be maintained asthe lithium ions are depleted from solution during deposition onto thecathode substrate. In addition, the anolyte circulation is crucial so asto minimize oxygen gas bubble accumulation on the anode. Bubbleaccumulation on the anode limits the anode surface area exposed to theanolyte, and can thus affect the rate of electrodeposition. Thoseskilled in the art will appreciate that the flow rate will depend on thesize and dimensions of the flow cell, which values can be predicted. Forcertain glass flow cell embodiments, flow rates of 5-80 mL/min work wellfor the electrodeposition process.

Another process parameter that can be varied is the salt used aselectrolyte. It has been found that various lithium salts such aslithium hexafluorophosphate (LiPF₆), lithium perchlorate (LiClO₄),lithium bisfluorosulfonimide (LFSI), lithium tetrafluoroborate (LiBF₄),and their mixtures thereof, can be dissolved in organic solvents such asacetonitrile (MeCN), dimethyl carbonate (DMC), ethyl methyl carbonate(EMC), ethylene carbonate (EC) and propylene carbonate (PC) to provide acatholyte that is at least 1 molar concentration in lithium ions. Ingeneral, thinner SEI coatings over each individual nanorod are observedwith lower concentrations of LiPF₆ (i.e., in mixtures with other lithiumsalts).

With regard to the current density, the current density (at fixedelectrodeposition time duration) primarily affects the length of thelithium metal nanorods, in that higher current densities result inlonger rod lengths and overall lithium metal film thickness. In oneembodiment, the current density is from 0.5 mA/cm² to 6 mA/cm²). Nanorodformation has been observed in electrodeposition runs performed atcurrent densities as high as 10 mA/cm². At current densities higher than10 mA/cm², the lithium metal morphology appears to be mossy growthrather than nanostructured.

With regard to the duration of electrodeposition time, the time (atfixed current density) primarily affects the length of the lithium metalnanorods, in that longer electrodeposition runs result in increased rodlengths and overall lithium metal film thickness.

In one embodiment, the lithium production results in lithium metalnanorods. The nanorods have a diameter of 250 nm to 400 nm. The nanorodshave a length of up to 60 μm at a current density of 6 mA/cm² for anelectrodeposition time of 40 minutes, which corresponds to the“thickness” of the deposited lithium layer. It is believed that ahemispherical tip is the most thermodynamically stable structure as itminimizes surface area. Dendrite formation is minimized at suchcontrolled current densities since the nanorod structure serves as anordered template for lithium metal deposition.

Turning back to the components of the system 100, again with referenceto FIG. 1, one embodiment of the system 100 includes the electrolyticcell 110 with a cathode 120 and anode 130. The cathode serves as thelocation for the electrodeposition of lithium. In general, theroom-temperature process previously described can yield conformalcoatings of thin lithium metal films, consisting of rods of uniformlength and diameter, onto the substrate of choice, even on substrateswith non-planar surfaces. In one embodiment, the deposited lithium maybe removed from the substrate for use as “bulk” lithium. Lithium metalproduction using the room-temperature electrodeposition process presentsadvantages such as energy savings (no need for heating to elevatedtemperatures) and environmental impact (only by-product is oxygen gas)over other “bulk” lithium generation processes.

In another embodiment, the cathode includes a substrate that is to servea substrate under the lithium. In terms of producing lithium metallaminates, the materials produced in accordance with the processesdescribed herein yield significantly better materials compared tolithium pressed and rolled onto a current collector. The latter cansuffer from delamination, thus causing areas of non-uniform electricalcontact with the current collector. In a particular embodiment, thecathode may comprise a substrate such as metal (e.g., Cu, Li) as well ascomposites such as carbon-coated metals (e.g., graphite on Cu) oroxide-coated substrates (e.g., Li₂S or LiAlO₂ on Cu) in the form ofsheets, foils, and foams. The cathode may be the same material as the“substrate” underneath the lithium foil. Alternatively the cathode andthe substrate may be different, such as for use of the substrate as asacrificial layer. The use of a different material may also be utilizeddue to their further alteration of the electrical properties of thelithium layer or due to particular morphological impacts on thedeposited lithium. The use of composite substrates (e.g., coatings suchas graphite and oxides) can lead to enhanced stability of the lithiummetal nanorods as anodes, by providing an additional SEI that cansuppress undesirable dendrite growth, formation of pockets of “dead”lithium (i.e., lithium metal that are electrically isolated from thecurrent collector) and side-reactions with electrolyte that consume theactive lithium metal. In particular, the ability to conformally coat allsurfaces of a foam with lithium metal via electrodeposition can realize3D-architectures for future battery configurations. Further, thesubstrate material may have a surface texture such as columnar orfibrous. These surface textures can increase the over-all surface areathat can affect battery cycling behavior by decreasing the voltage dropacross the electrodes. In addition, the substrate may undergo apre-treatment such as acid pre-wash or plasma treatment to removesubstrate surface impurities, or with a pre-coating of carbon or oxide(e.g., via atomic or molecular layer deposition) to create an artificialSEI that should be thin enough and lithium- and electron-conductive toallow for lithium metal deposition between the underlying currentcollector and the artificial SEI.

The cathode is associated with a catholyte. The catholyte serves as theelectrolyte for the cathode. In one embodiment, the catholyte includes alithium salt in an organic solvents. For example, the lithium salt maybe selected from LiPF₆, LiClO₄, LiBF₄, LiFSI, or combinations thereof.The organic solvent may be selected from DMC, EMC, PC, MeCN orcombination thereof. In one embodiment, more than one salt and/or morethan one solvent may be used to form the catholyte.

With continued reference to FIG. 1, the anode comprises an anodematerial. For example, in one embodiment a platinum group material, suchas platinum, platinum-coated titanium, platinum-coated steel (e.g.,SS316) or platinum-coated copper sheets, foil or foam.

The anode is associated with an anolyte. The anolyte serves as theelectrolyte for the anode. In one embodiment, the anolyte includes alithium salt in a water solvent. For example, the lithium salt may beselected from Li₂CO₃, LiHCO₃, Li₂SO₄, LiHSO₄ or combinations thereof. Inone embodiment, more than one salt and/or more than one solvent may beused to form the anolyte. In general, the pH of the anolyte solution maybe adjusted to be as neutral as possible (i.e., pH 7) with the use oflithium bases such as Li₂CO₃ in order to minimize hydrogen ionconcentration and reduce the possibility of co-reduction on the cathodeas hydrogen gas.

The electrolytic cell 110 includes the anode and the cathode separatedby a lithium ion conducting membrane. The lithium ion conductingmembrane further maintains physical separation of the anolyte and thecatholyte. The membrane 140 is a nonporous hybrid membrane that allowsfor asymmetric media (e.g., aqueous on one side, organic on the otherside) while limiting transport to lithium ions by facilitated diffusionthrough the membrane. For example, in one embodiment the membrane may beinorganic, such as commercially available ceramic membranes. Further,the membrane may be an organic polymer or a hybrid organicpolymer-inorganic composite. In one embodiment, the membrane has thefollowing properties: (1) does not allow the movement of water from theanode to the cathode, since the lithium metal being deposited on thecathode will react with water; (2) ion-conducting, but not necessarilylimited to lithium ions, as it is easier to pre-treat the lithium ionfeedstock and control its impurities; (3) stable against both aqueousand organic media; (4) sufficient dielectric stability so as not to haveits structure compromised during electrodeposition runs (voltages canapproach 10V). Commercial membranes, such as the lithium-ion conductingglass by Ohara Corporation, can be used, as well as any other compositemembranes with lithium-ion conductors embedded in a non-porous matrix.

FIGS. 5A-D show an experimental proof-of-concept. The proof-on-conceptexperiment was performed in a glass see-through cell, in lieu of aconventional coin cell format. The electrodeposited lithium film ofinitial thickness 30 μm (i.e., length of the rods) on copper foil wasused as an anode and initially discharged. In this symmetricalconfiguration, the cathode was an initially bare copper foil and thepurpose of the discharge test was to determine if we can successfullymove the lithium from the anode to the cathode. FIG. 5C shows successfulmovement of the lithium from the anode (now reduced in thickness, perFIG. 5B) and plated it onto the copper cathode. In the second part ofthis test, the anode was then charged and it can be seen that additionallithium is deposited as a continuation of the rods. Rather than themossy, dendritic growth normally observed, the additional depositioncontinues as rods. The prior art mossy growth is a non-structuredlithium growth that can lead to battery failure as a result of thedendrites piercing the separator, leading to shorting of the cell.

Further experiments were performed with coin cell tests where theelectrodeposited lithium nanorods were used as anodes against variouscathode materials such as bare copper, electrodeposited lithium oncopper foil (symmetrical coin cell), and conventional electrodes used inlithium-ion batteries, such as NMC 532, LTO and graphite on copper.These experiments exhibited excellent cycling (at least 100discharge/charge cycles) for both symmetrical and asymmetric (vs. NMC532) coin cells. FIGS. 5E-G show data from these experiments.

Glass Flow Cell

In another embodiment, the system 200 for production of lithiumcomprises a glass flow cell assembly 210 with a lithium permeablemembrane 240 for room-temperature lithium-metal synthesis (FIG. 6). Inthe embodiment of FIGS. 6 and 7, two half-cells (cathodic half-cell 224and anodic half-cell 234). Each of the half-cells are, for example, madefrom glass vessels (Part No. 6 in FIG. 1) that are connected via apassage 244. The passage regulated by a membrane 140 that is permeableto lithium ions, for example, a hybrid polymer-inorganic oxidenanocomposite membrane. The membrane 140 is a nonporous hybridorganic-inorganic composite that can be used with asymmetric media ineither compartments (e.g., aqueous in one, organic in the other side)while limiting transport to lithium ions by facilitated diffusionthrough the inorganic components. An ideal structure for the membraneinvolves a polymeric framework or support. The membrane impartsflexibility and its composition is stable in both aqueous and organicmedia, in addition to having a high dielectric stability to withstandpotential biases typically present in system 200 during operation.

The embedded cross-linked nanoparticles can be lithium ion conductors(e.g., lithium iron phosphate (LiFePO₄), lithium titanium oxide (“LTO”),lithium cobalt oxide (“LCO”), lithium lanthanum zirconium oxide(“LLZO”), and lithium versions of NASICON-type ceramics (e.g., OharaLICG powders), including as silica-coated materials) and need to beexposed to the electrolyte solutions in either compartments beingseparated. The use of asymmetric media is critical to this process (dueto incompatibility of lithium metal to water) and thus requires amembrane that will prevent mixing of the organic and aqueous phaseswhile allowing for ion transport. One such membrane is described below.

Further, the cathode half-cell includes a cathode electrode holder 222and the anode half-cell includes an anode electrode holder 232. Thecathode electrode holder 222 (and the anode electrode holder 232) can beformed to facilitate two-side deposition by exposure of two sides of theelectrode or single side formation by exposure of a single side.Further, in the embodiment of FIGS. 6 and 7, it is provided with ananolyte circulation system and a catholyte circulation system to flowthe respective electrolyte through the respective half-cell. Electrolytecirculation can contribute to enhanced uniformity of the morphology ofthe resulting Li-metal films by minimizing concentration gradients andbuild-up of detrimental by-products (if any) at the Li-metal/electrolyteinterface.

Ion-Conducting Membrane

In one embodiment, the ion-conducting membrane is a hybridorganic-inorganic nanocomposite membrane. The hybrid organic-inorganicnanocomposite is a nonporous hybrid organic-inorganic composite that canbe used with asymmetric media in either compartments (e.g., aqueous inone, organic in the other side) while limiting transport to lithium ionsby vacancy diffusion through the inorganic components.

FIG. 9 illustrates one embodiment of an ideal structure for the hybridorganic-inorganic nanocomposite membrane involves a polymeric frameworkor support 921 that contains an array of columns of inorganic lithiumion conductor 911. The polymer mesh imparts flexibility and itscomposition (e.g., propylene, polyurethane, polyethylene oxide (“PEO”),polyethylene glycol (“PEG”)) chosen as to be impermeable to and stablein both aqueous and organic media, in addition to having a highdielectric stability to withstand potential biases typically present indevices during operation. In one embodiment, the columns of solidlithium ion conductor comprise solids and may be a monolithic piece,such as a single particle or may be a plurality of interconnectedparticles forming a pathway through the polymeric framework. In oneembodiment, the interconnected particles are nanoparticles. Solidlithium ion conductor columns (e.g., lithium ion conductors, such assilica-coated LiFePO₄, LLZO, etc.) may directly span the polymer networkin a linear fashion or traverse in a nonlinear path, so long as theyprovide a single structure or interconnected particles that form linearor nonlinear “channels” of lithium ion transport from anolyte tocatholyte.

Many lithium ion conductors reported in literature require some form ofheat-treatment either from sol-gel methods or from molten glassreactions. Elevated temperatures, however, are not expected to becompatible with the polymer-based frame described above. The hybridorganic-inorganic membrane is fabricated through room-temperaturesynthesis and integration of the ion conducting solid into the polymericframe. In one embodiment, the hybrid organic-inorganic membrane is aporous polymer matrix filed with lithium ion conducting particles andimpermeable to the aqueous and organic electrolytes. In a secondembodiment, a porous polymer matrix is filed by sequential filtrationthrough the matrix of a first monomer with the lithium ion conductingparticles suspended therein and then a second monomer solution. Thefirst and second monomer react by interfacial polymerization to form anorganic component that seals the polymer matrix at one side of themembrane.

With regard to that first membrane embodiment, a polymer framework is aporous polymer framework. assembled having the necessary aligned columns(pores) to accommodate a solid lithium ion conductor exposed on bothsides (anode side and cathode side of the membrane). The polymer must bestable upon application of voltage up to 10 V and must not be solublenor react with anolyte and catholyte. In one embodiment, the lithium ionconductors for have ionic conductivities of magnitude 10⁻⁷ to 10⁻⁴ S/cm.In one example, a porous polymer framework may be 3D printed. In furtherembodiments, other printing methods such as polymer pen lithography ordip pen lithography may be utilized. The size of the pores will bedictated by the particulate size of the lithium ion conducting fillersthat will be used. While, the pores need not be perpendicular to themembrane cross-section, slanted pores lead to longer diffusion times forthe lithium ions from the anolyte to the catholyte. It is preferred tohave as high a pore density as possible to ensure sufficient rates oflithium ion replenishment in the catholyte. Pore densities willinversely depend on the pore size. In one embodiment, pore diameters of1-1000 μm will work well with this electrodeposition process. Theaverage center-to-center distance will be limited by the printingtechnique, but generally would be preferred to be the minimum widthallowable for the printed porous polymer frame to maintain structuralsupport. A 3D printer may be employed for the preparation of such amembrane to ensure uniformity and to achieve a close-packed array of theion conducting components, while allowing for excellent control ofmembrane dimensions (size of overall piece, diameter of inorganiccolumns, etc.). In one embodiment, the polymer frame and the lithium ionconducting material are simultaneously printed or printed together, suchas using dual nozzles. Alternatively, the porous polymer frame can be3D-printed first, followed by filling in the pores with a slurry of thelithium ion conductors.

The porous polymer framework is then filled, specifically the pores,with lithium ion conducting particles. In one embodiment, the lithiumion conducting particles can be uniformly dispersed in a precursorsolution or slurry that can cure at room-temperature into a flexiblesolid film upon solvent evaporation, or a mixture of pre-polymers withreactive end moieties that react at room-temperature (e.g., “clickchemistries”) to form a solid covalent network. To ensure structuralintegrity of the resulting membrane, the interface of polymer and solidion conducting phases must be in intimate contact (i.e., no spaces orgaps for either electrolyte solvents to diffuse into via capillaryforces) via either covalent bonding or noncovalent intermolecular forcesof attraction such as van der Waals forces between the polymeric frameand the surfaces of the ion-conducting particles. Other methods toprepare such membranes include: the inorganic component may be extrudedas a concentrated slurry in a fast-evaporating solvent, or may be castonto the pre-fabricated polymer framework, which may then be followed byan encapsulation step to make sure the lithium ion conducting phases donot leach from the membrane and into either electrolyte compartments.

FIGS. 10A-C show one embodiment of 3D printed polymer framework, not yetloaded with a solid lithium ion conductor. FIG. 10A shows the membraneand a membrane holder for positioning the membrane in the lithiumelectrodeposition apparatus. FIG. 10B shows a top down view of oneembodiment of a 3D printed membrane. FIG. 10C shows the membrane of FIG.10B positioned in a bottom portion of a membrane holder for the lithiumelectrodeposition apparatus. The membrane holder may comprise an anodecompartment and a cathode compartment in a two-part structure with themembrane disposed there between. The membrane holder comprises amaterial that is stable in either water (for the anode half-cell) or inorganic solvent (for the cathode half-cell), preferably both. Bothhalf-cells must be stable when separated by the membrane under thebiases typically used during electrodeposition. In one embodiment, the3D printed membrane can be used with various lithium ion conductors,such as LiFePO₄ and NASICON type powders (generally,Na_(1+x)Zr₂Si_(x)P_(3−x)O₁₂, 0<x<3), such as Li₂O—Al₂O₃—SiO₂—P₂O₅—TiO₂.The former exhibited an ionic conductivity ˜10⁻⁹ S/cm while the laterexhibited an ionic conductivity ˜10⁻⁴ S/cm.

In another embodiment of an ion-conducting membrane, the membraneincludes a polymer matrix and a lithium ion conductor, such as aLiFePO₄, that affixed within the polymer matrix, such as onto thesurface of polymer supports within the polymer matrix. The polymermatrix is porous, thus the electrolyte solution readily seeps into itspores to interact and “wet” the lithium-ion conducting solids. Thelithium ion conductor can be affixed by a polymer through mixture of theconductor with one or more monomers prior to polymerization. In theexamples illustrated, the polymer matrix is a porous matrix (e.g.,polypropylene/polyethylene/polypropylene (PP/PE/PP) membranes sold asCelgard® membranes) and the lithium ion conductor is disposed in thepolymer matrix by interfacial polymerization (FIGS. 11A-C), such as withan organic support layer. In alternative embodiments, the polymers thatcan be used include polyurethane, polyethylene glycol (aka polyethyleneoxide), polyamide, polystyrene. Further, other methods besidesinterfacial polymerization can be utilized, for example but not limitedto cure over time or by heating or UV illumination. It has been foundthat ionic conductivities of magnitude 10⁻⁷ to 10⁻⁴ S/cm work well aslithium ion conductors for this electrodeposition process. The polymerwill ideally seal the nanoparticles within the polymer matrix, anddepending on its thickness (which can be controlled by etching) can forma layer on one side. Any unreacted monomers and/or by-products aretypically washed out after polymerization. The secured ion conductorneed not extend completely through the membrane polymer support in thisembodiment, as the ions are able to travel through the polymer supportlayer, so the conductor only need exposure to be wet on one side (hencethe control of the polyamide layer thickness described below).

In the example embodiment using interfacial polymerization, the reactionat the interface of an aqueous and an organic solution containing anamine (m-phenylenediamine) and a carbonyl compound(1,3,5-benzenetricarbonyl chloride). In further embodiments, any primaryamine RNH₂ (where R=alkyl, aromatic, etc.) can be used, and anyactivated carbonyl compound (acyl COCl, etc.) can be employed. In oneparticular embodiment, the ion conductor, such as LiFePO₄, is suspendedin an aqueous solution of a Monomer A (such as, m-pheynylenediamine).The suspension mixture of Monomer A and the LiFePO₄ is filtered throughthe polymer matrix (e.g., polyethylene/polypropylene substrate) at 40PSI. It should be appreciated that the pressure can be varied and withlower pressure preferred. A second monomer, Monomer B (such as1,3,5-benzenetricarbonyl chloride) dissolved in organic solvents such ashexane, is then poured onto the polymer matrix having the Monomer A andLiFePO₄ mixture. The exposure of the monomer B is preferred to not bedone by submersion, as it may lead to blockage of the Celgard® pores onthe other side of the substrate. In one embodiment, pouring is donecarefully and slowly so as to minimize perturbation of the compactedlithium ion conductors on the polymer matrix. The monomer A/monomer Btechnique utilizes interfacial polymerization (i.e., Monomers A and Breact at the interface of the immiscible layers). Filtration of MonomerB is not recommended. Monomers A and B reacted to form a polyamide, thethickness of which is controlled by the monomer concentrations. Theresulting polyamide thickness is minimized to not hinder lithium iontransport. Illustrated below is a schematic of a polyamide formationbetween an amine and an activated carbonyl compound.

Thus, the ion conducting solids LiFePO₄ are encapsulated onto Celgard®by the thin polyamide layer.

In one embodiment, the resultant membrane can be treated afterpolymerization to ensure that the lithium ion conducting solid will bewet by the electrolyte, that is that it remains exposed on both sides ofthe membrane. An etchant or depolymerizating agent may be used to cleavethe bond between the monomers, such as between Monomer A and Monomer B,to control thickness of the polymer layer. FIG. 13 illustrates theresults of one embodiment using differing amounts of Pronase E where them-phenylenediamine and a carbonyl compound 1,3,5-benzenetricarbonylchloride were used as the monomers to polymerize around LiFePO₄.

Example

An experiment was carried out to create a lithium ion conductingmembrane as described above. This experiment utilized bare Celgard® andpolyamide-modified Celgard® membranes as controls with no lithium ionconducting solids. The tested embodiment of a membrane comprisedpolyamide+LiFePO₄+Celgard® membranes. The membranes were used in a setupsimilar to shown in FIG. 1 for electrodeposition of lithium. Apre-treated copper foil was used as the cathode. 1M LiPF₆ in DMC wasused as the catholyte. The anode was platinum with the anolyte beingsaturated aqueous Li₂SO₄ with a pH of 3-4.

The electrodeposition was run for 40 minutes at −2.5 mA/cm². The resultswere observed as follows:

-   -   (PP/PE/PP) membranes (Celgard®) only membrane: effervescence        (H₂) off electrodeposited Li metal due to trace water through        membrane    -   (PP/PE/PP) membranes (Celgard®)/Polyamide membrane: no        effervescence on Cu foil, minimal Li metal deposited    -   (PP/PE/PP) membranes (Celgard®)/LiFePO₄/Polyamide membrane: no        effervescence on electrodeposited Li metal.

The results show that the (PP/PE/PP) membranes (Celgard®)/Polyamidemembrane fails to function to deposition lithium, at least anappreciable amount. In the experiment with just (PP/PE/PP) membranes(Celgard®), electrodeposition of lithium metal was still observedbecause the lithium ions in aqueous anolyte were still able to diffusethrough the (PP/PE/PP) membranes (Celgard®) pores; however, this alsomeant that water was getting into the catholyte, and thus reacting withthe electrodeposited lithium metal: 2 Li_((s))+2 H₂O_((liq))→2LiOH+H_(2(gas)). There was no appreciable lithium metal electrodepositedusing the (PP/PE/PP) membranes (Celgard®)/polyamide membrane since thenonporous polyamide sealed off the (PP/PE/PP) membranes (Celgard®) poresbut without providing a means for lithium ion transport. Thus, thecircuit between the half-cells was effectively open, large IR dropacross the (PP/PE/PP) membranes (Celgard®)/polyamide membrane.

ALD/SIS Membrane

In another embodiment, the membrane is coated with an inorganic materialon one or both sides, or deposited within the membrane's polymerdomains, to minimize undesirable swelling upon immersion in both aqueousand organic media (FIGS. 13A-C). The membrane includes a polymer matrixand a lithium ion conducting material. The membrane may be PEO, as inthe examples below, or other polymer materials described above, such as(PP/PE/PP) membranes (Celgard®). The inorganic material may be depositedby atomic layer deposition (“ALD”) or sequential infiltration synthesis(“SIS”). In such embodiments, a lithium ion conducting material isembedded in a polymer film to form the membrane and one or more sides ofthe membrane are coated with the inorganic component. The inorganicmaterial may be deposited to a thickness of 1 to 10,000 atoms, such as1-2,000, 1-1,000, 1-100, 10-100, and 10-1000 atoms thick.

In one embodiment, the membranes are hybrid organic-inorganic compositemembranes where inorganic components, such as oxide nanoparticles, arecovalently networked by organic polymer (e.g., hydrocarbons such asPEO/PEG, polystyrenes, etc.) chains. Inorganic components that arelithium conducting can be used in one embodiment.

The membrane comprises a polymer framework. A layer of polymer materialdefines the membrane and the ion-conducting material is then embeddedtherein. The polymer should be selected based on the intendedapplication, but in embodiments for use in the electrodepositionapparatus described, the polymer should be stable in both an aqueousenvironment and an organic, nonaqueous environment. Preferably, thepolymer material will have a high dielectric stability to withstand thebias within the apparatus. The polymer may be silica-based polyurethane,a PEO polystyrene or polyamide. Polystyrene can provide enhancedrigidity compare to PEO of the same thickness; polyamide can provideenhanced stability in both aqueous and most organic solvents compared toPEO.

The lithium ion conducting material may be a suitable material that maybe deposited by ALD/SIS. For example, LiCoO₂,Li_(i+x+y)Al_(x)Ti_(2−x)Si_(y)P_(3−y)O₁₂. Alternatively, one can alsoincorporate inherent lithium ion conductors such as lithium ironphosphate (LiFePO₄), LTO, LCO, LLZO, and lithium versions ofNASICON-type ceramics (e.g., Ohara LICG powders).

In a further embodiment, the inorganic components can be not inherentlylithium-ion conducting that are doped to impart this property, such assilica, alumina, and titania. One way to achieve this is to introducestrongly bound (via electrostatic forces) lithium ions onto thenegatively charged surfaces of silica nanoparticles via well-knowntechniques such as strong electrostatic attraction (“SEA”) or byincipient wetness impregnation (“IWI”). These two techniques are widelyused for loading metal sites for the synthesis ofsupported/heterogeneous catalysts. To the best of our knowledge, this isthe first report of the use of SEA/IWI to prepare separators for batteryapplications. Alternatively, one can also incorporate inherent lithiumion conductors such as lithium iron phosphate (LiFePO₄), LTO, LCO, LLZO,and lithium versions of NASICON-type ceramics (e.g., Ohara LICGpowders).

The ion-conducting aspect of the membrane may be imparted by one or bothof having the ion conducting materials extend the thickness of themembrane, thus being exposed to both the cathode side catholyte and theanode side anolyte and/or ion hopping via lone pair donors on thepolymer backbone. Lithium ion transport can be achieved through lithiumion conducting solids through a process called “vacancy diffusion” wherethe lithium ion moves from one point to another throughout thecrystalline lattice. On the other hand, lithium ions are transported bynon-lithium ion conductors via “hopping” mechanism where the positivelycharged lithium ion hops from one lone pair of electrons (electrostaticattraction) to another. These lone pair of electrons are typically onelectronegative atoms such as F, O, or N on polymer backbones (the Oatom in PEO/PEG, N atom in polyamides, or F in fluorinated polymers) oron oxide surfaces.

Once this hybrid organic inorganic membrane is prepared, the membrane isthen subjected to an ALD/SIS treatment. Most ALD/SIS precursors employedreact with hydroxyl/hydroxide (—OH) moiety that can be present either onthe organic polymer network or on the surfaces of the embedded oxideparticles, for example but not limited to ZnO, ZrO₂, Al₂O₃, SiO₂, TiO₂,Li₂S, LiAlO₂. Experiments included Al₂O₃ or ZnO coatings of uniformthickness on both sides of the hybrid organic-inorganic compositemembrane from ALD/SIS precursors trimethylaluminum (“TMA”) ordiethylzinc (“DEZ”), respectively. Because these coatings are very thin(<5 nm on each side), they do not pose a barrier to lithium iondiffusion and transport from the electrolyte and through the membrane.

The coating may be done by a method chosen from ALD, Molecular LayerDeposition (“MLD”), and SIS.

FIGS. 14A-C shows an elemental analysis via XREF of one embodiment of amembrane (FIG. 14A) and of membranes fabricated by ALD/SIS treatment(FIGS. 14B-C). The XREF signal (y-axis) is plotted as a function ofphoton energy (x-axis, units keV). FIG. 14A shows the untreatedmembrane; FIG. 14B shows a TMA/H₂O treated membrane has been coated withaluminum oxide; FIG. 14C shows a DEZ/H₂O treated membrane has beencoated with zinc oxide. As seen in FIG. 14A, the elemental analysis ofillustrates that the untreated membrane demonstrates the presence ofsilicon. This corresponds to the of silicon dioxide nanoparticles, and acorresponding major peak centered around ˜1.8 keV (x-axis). Turning tothe two samples treated by ALD/SIS treated membranes show identicalsignals in all but two regions. As seen in FIG. 12B, a TMA/H₂O treatedmembrane has been coated with aluminum oxide, shows a peak centeredaround ˜1.5 keV corresponding to aluminum. Further, FIG. 12C and (ii)DEZ/H₂O treated membrane (green, bottom) has been coated with zincoxide, and thus shows a peak centered around ˜8.6 keV corresponding tozinc. Such data demonstrates that the membranes can be furtherfunctionalized via ALD and SIS, most notably to an even wider class ofother coatings typically found in ALD/SIS processes.

Such data demonstrates that the membranes can be further functionalizedvia ALD and SIS, most notably to an even wider class of other coatingstypically found in ALD/SIS processes. The ALD/SIS process can be used toalter additional properties of the membrane, for examplehydrophobicity/hydrophilicity or current flow or ion permeability, aswell as to tune wetting properties and dielectric stability. Forexample, a hydrophilic membrane such as PEO could be coated via ALD witha thin, ion permeable inorganic coating that reduces the hydrophilicityor changes the surface to be hydrophobic.

The coating of bare membrane material reduces the swelling observed inmembrane materials. In particular, hydrophilic polymers such as PEO,polyelectrolytes such as polymethacrylic acid and polyamines will swelldue in water or in polar organic solvents such as alkyl carbonates(dimethyl carbonate, ethyl methyl carbonate, propylene carbonate,ethylene carbonate). The reduced swelling improves the resistance of thetreated membrane to water permeation compared to the bare membrane.

In one embodiment, an alumina overcoat is applied to a membrane and issufficiently thin to allow ion transport through the overcoat. Forexample, 30 cycles of alumina to deposit a 4 nm thick overcoat, such ason one side or both sides of the membrane.

In another embodiment, zinc oxide overcoat is applied to a membrane andis sufficiently thin to allow ion transport through the overcoat. Forexample, 30 cycles of zinc oxide to deposit 4 nm thick overcoat, such ason one side or both sides of the membrane.

FIG. 15 illustrates one embodiment where thin film layers of Al₂O₃ arecoated on a membrane, PEO and SiO₂ hybrid membrane in the illustratedembodiment.

In one particular example, a novel composite was prepared wherecommercially available lithium ion conducting powders (e.g., Ohara) isimparted with a thin silica overcoat via sol-gel methods, and the silicasurfaces covalently modified with an oligomeric cross-linker. Theoligomers on the silica surfaces then further react to form a networkformed such as shown below using an isocyanate and an alcohol.

As used herein, the singular forms “a,” “an,” and “the” include pluralreferents unless the context clearly dictates otherwise. Thus, forexample, the term “a member” is intended to mean a single member or acombination of members, “a material” is intended to mean one or morematerials, or a combination thereof.

As used herein, the terms “about” and “approximately” generally meanplus or minus 10% of the stated value. For example, about 0.5 wouldinclude 0.45 and 0.55, about 10 would include 9 to 11, about 1000 wouldinclude 900 to 1100.

It should be noted that the term “exemplary” as used herein to describevarious embodiments is intended to indicate that such embodiments arepossible examples, representations, and/or illustrations of possibleembodiments (and such term is not intended to connote that suchembodiments are necessarily extraordinary or superlative examples).

The terms “coupled,” “connected,” and the like as used herein mean thejoining of two members directly or indirectly to one another. Suchjoining may be stationary (e.g., permanent) or moveable (e.g., removableor releasable). Such joining may be achieved with the two members or thetwo members and any additional intermediate members being integrallyformed as a single unitary body with one another or with the two membersor the two members and any additional intermediate members beingattached to one another.

It is important to note that the construction and arrangement of thevarious exemplary embodiments are illustrative only. Although only a fewembodiments have been described in detail in this disclosure, thoseskilled in the art who review this disclosure will readily appreciatethat many modifications are possible (e.g., variations in sizes,dimensions, structures, shapes and proportions of the various elements,values of parameters, mounting arrangements, use of materials, colors,orientations, etc.) without materially departing from the novelteachings and advantages of the subject matter described herein. Othersubstitutions, modifications, changes and omissions may also be made inthe design, operating conditions and arrangement of the variousexemplary embodiments without departing from the scope of the presentinvention.

While this specification contains many specific implementation details,these should not be construed as limitations on the scope of anyinventions or of what may be claimed, but rather as descriptions offeatures specific to particular implementations of particularinventions. Certain features described in this specification in thecontext of separate implementations can also be implemented incombination in a single implementation. Conversely, various featuresdescribed in the context of a single implementation can also beimplemented in multiple implementations separately or in any suitablesubcombination. Moreover, although features may be described above asacting in certain combinations and even initially claimed as such, oneor more features from a claimed combination can in some cases be excisedfrom the combination, and the claimed combination may be directed to asubcombination or variation of a subcombination.

What is claimed is:
 1. An hybrid inorganic/organic membrane comprising:a polymeric matrix; a plurality of ion-conducting particles disposedwithin the polymeric matrix, the plurality of ion-conducting particlesforming ion conducting channels in the polymer matrix; and an inorganiccoating deposited in the polymeric matrix, the inorganic coating being auniform layer 1 to 10,000 atoms thick.
 2. The hybrid inorganic/organicmembrane of claim 1, wherein the inorganic coating is ion-permeable andthe hybrid inorganic/organic membrane is impermeable to both aqueous andorganic media.
 3. The hybrid inorganic/organic membrane of claim 1,wherein the inorganic coating is covalently bonded.
 4. The hybridinorganic/organic membrane of claim 1, wherein the inorganic coatingcomprises a metal oxide.
 5. The hybrid inorganic/organic membrane ofclaim 1, wherein inorganic coating comprises a material selected fromthe group consisting of alumina (Al2O3), zirconia (ZrO2) and zinc oxide(ZnO).
 6. The hybrid inorganic/organic membrane of claim 1, wherein thepolymeric matrix comprises a solid matrix with through-pores and furtherwherein each of the through-pores are filled with ion-conductingparticles.
 7. The hybrid inorganic/organic membrane of claim 1, whereinthe ion-conducting particles comprise a material selected fromcrystalline solids and non-crystalline solids.
 8. The hybridinorganic/organic membrane of claim 7, wherein the crystalline solidsare selected from the group consisting of LiFePO4, lithium lanthanumzirconium oxide (LLZO), lithium titanium oxide (LTO), lithium cobaltoxide (LCO), and NASICON-type Li2O-Al2O3-SiO2-P2O5-TiO2.
 9. The hybridinorganic/organic membrane of claim 7, wherein the non-crystallinesolids comprise lithiated silica.
 10. A method of making a hybridinorganic/organic membrane comprising forming a polymer framework havinga plurality of pores; and integrating a plurality of ion conductingparticles into the polymer framework.
 11. The method of claim 10,wherein integrating the plurality of ion conducting particles comprises:forming a slurry comprising the plurality of ion conducting particles;and applying the slurry to the polymer framework.
 12. The method ofclaim 11 wherein the plurality of ion conducting particles comprise amaterial selected from LiFePO4 and NASICON-type powder.
 13. The methodof claim 12, wherein forming the polymer matrix comprises 3-D printing.14. The method of claim 10, wherein integrating the plurality of ionconducting particles comprises: forming an aqueous mixture of lithiumion conducting particles suspended in an aqueous solution of a firstmonomer; filtering the aqueous mixture through the polymer framework andcapturing the lithium ion conducting particles within the polymermatrix; rinsing a hexane solution of a second monomer through thepolymer matrix; and reacting the first monomer and the second monomer tofix the ion conducting particles within the polymer framework andforming a polymer layer on a first side of the membrane.
 15. The methodof claim 14, wherein the polymer layer is a polyamide layer.
 16. Themethod of claim 15, wherein the first monomer is an amine suchm-phenylenediamine and the second monomer is an activated carbonylcompound such as 1,3,5-benzenetricarbonyl chloride.
 17. The method ofclaim 14, further wherein the polyamide layer is etched.
 18. The methodof claim 17, wherein the polyamide layer is etched by application of aprotease.